Variable load brake



Oct. 24, 1933. E. K. LYNN VARIABLE LOAD BRAKE Filed Feb. 19. 195o .h .fN.mW/.VM m. `M\om. ITN mh.

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n :6555 aan y v IUETWW- INVENTOR EWING K. LYNN BY ATTORNEY Patented Oct.24, 1933 UNHTED STATES PATENT GFFECE VARIABLE LOAD BRAKE Ewing K. Lynn,

Application Februar This invention relates to East Melieesport, Pa.,assigner tc rEhe Westinghouse Air Brake Ccmpany, Wilmerding, Pa., acorporation of Pennsyl- Vania 19 Claims.

devices for varying the braking power on a vehicle according to the loadand more particularly to the means which are automatically operativeforlocking such devices in their adjusted posi tions.

Heretofore, in variable load brake apparatus,

it has been proposed to mechanisms of various said apparatus in variousa it has been discovered that not always operate to mai of the apparatussuch that use ratchet locking types for maintaining djusted positions,but these mechanisms do ntain the adjustment curately limit the brakecylinder pressure according to the load on the vehicle.

The reason for this is that in these mechanisms the minimum adjustmentwhich can be obtained is the space between two adjacent ratchet teeth,

and when the load on the car is such that the locking pawl will notengage either one of these teeth, the adjustment can apparatus willoperate to not be held and the release the adjustment until the ratchetpawl engages the next tooth, thus decreasing the lating spring.

pressure of the regu- In these ratchet mechanisms, the ratchet teeth arearranged as close together as possible so as to provide for linevariations in brake cylinder pressure according to the load on the car,but

it has been found that when the teeth are arranged so as to providethese fine variations, they are not strong enough to withstand theforces to which they are subjected and break and impair the operation ofthe appar The principal object of my invention is atus.

to provide a variable load brake apparatus for a vehicle which willoperate t o accurately regulate the braking power accordingr to the loadon the vehicle and whichv is well adapted to withstand the forces towhich it is subjected in service.

Another and more specifi tion is to provide a frictio for a variableload brake c object of my invenn locking mechanism apparatus which willeiiectively maintain said apparatus in any of its various adjustedpositions.

Other objects and advantages of my invention will appear in thefollowing detailed description.

In the accompanying drawing;

mainly in section,

diagrammatic view,

Fig. 1 is a of one form of variable load brake apparatus embodying myinvention; and Fig.

2 is a plan view of a portion of the apparatus as viewed in thedirection of the arrow in Fig. l.

In the present embodiment of the invention as shown in the drawing,

the reference charwill operate to acacter 1 indicates a portion of avehicle body which is supported on the usual vehicle trucks,

a portion 2 of one of said trucks being illustrated. Carried by the carbody is a variable load brake apparatus which may comprise a brakecylinder pressure limiting valve device 3, a strut cylinder device Ll, alocking mechanism 5, a brake cylinder 6 and a door engine 7.

The brake cylinder pressure limiting valve device 3 may comprise acasing in which there is 65 mounted a iiexible diaphragm 8, which isoperative to control the operation of a supply valve 9 contained in avalve chamber 10. Also contained in the chamber 10 is a spring 11 whichis interposed between a cap nut 12,'having screw- 70 threaded connectionwith the casing, and one side of the valve 9,y the pressure of whichspring tends to seat the valve 9.

The supply valve chamber 10 is constantly connected to the service portof the usual brake application valve, (not shown), through a passage andpipe 13. The chamber 14, at one side of the flexible diaphragm 8 isconstantly connected to the brake cylinder 6 through a passage and pipel5.

Contained in a chamber 16, atthe other side of the flexible diaphragm 8and engaging the diaphragm, is a follower 17, which is subject to thepressure of an adjustable spring 1S, said spring being adjusted by meansof a plunger 19, which is slidably mounted in the open end portion ofthe casing, and which is in engagement with the outer end of the spring18.

Having screw-threaded connection with the plunger 19 and extendingoutwardly therefrom, 9o is a bolt 2O having a head 21 which is adaptedto be engaged by an arm 22 secured to a shaft 23, rotatably mounted inspaced brackets 24 which may be integral with the casing of a portion ofthe locking mechanism 5 or any other fixed part 95 of the apparatus orvehicle body.

Also secured to the shaft 23 and arranged between the brackets 24 is anarm 25 which, at its free end, is provided with a curved surface 26preferably in the form oi an arc of a circle 100 struck from a centerslightly above a point corresponding with the axis of the shaft 23.However, if desired, this surface may be made in the form of an arc of acircle struck from a point corresponding with the axis of the shaft 23.

The strut cylinder device 4 may comprise a casing containing a piston 27having a stem or strut 28 which extends through an opening in the outerend of the casing and which, adjacent its outer end, is operativelyconnected to a 110 of the casing.

lower or outer end portion of fi, end portions of these lever 29 by apin 30. The chamber 31 at one side of the piston 27 is constantlyconnected to a passage and pipe 32, which, in the present embodiment ofthe invention, is the usual door opening passage and pipe. The chamber33, at the other side of the piston 27, contains a spring 34, thepressure of which tends to urge the piston toward the left hand.

A lso secured to the shaft 23, is an arm 35, the free end of which isoperatively connected to one end of the lever 29, at one side of the pin30, by a link 36 and pivot pins 37 and 38, vthe pin 37 passing throughthe arm and the link 36 and the pin 38 passing through the lever 29 andlink 36. At the other side of the pin 30, the end of the lever 29 isoperatively connected to the inner end of a link or rod 39 through themedium of a pin 40. The outer end of this rod 39 is operativelyconnected to the arm 4l of a bell crank, by a pin ally mounted on thevehicle body. The other arm, 43, of the bell crank is adapted uponmovement of the rod 39, in the direction toward the right hand, to movea roller 44, carried by the arm 43, into engagement with the portion 2of the vehicle truck.

The locking mechanism 5 lmay comprise a casing containing a piston '45having a stem 46 which extends through an opening in one end vThechamber 47, at one side of the piston 45, is constantly connected to thepassage 32. The chamber 48, 'at the other side of this piston, containsa spring 49, the pressure of which tends to move the piston and its stemupwardly.

Arranged between the brackets 24 vis a lever 50 which is pivotallymounted, intermediate its ends, on a pin 51 carried by the brackets 24.One end of this lever is operatively connected with the the piston stem46 by means of a pin 52 and operatively rconnected to the other end ofthe lever by a pin 53, and extending upwardly therefrom are spaced links54. Arranged between and carried by the upper links is a frictionlocking element Vwhich is adapted to be moved into and out of frictionallocking engagement with the surface 26 of the arm V25 and a surface 56formed on a lug 58 extending outwardly .from the casing of the lockingmechanism. :The surface 56 is so disposed that as the links 54 are moveddownwardly, the element 55 will be wedged between the surfaces 26 and 56of the arm 25 and lug 58, respectively, and thus lock the arm 25 in anadjusted position.

In the present embodiment of the invention, the friction locking element55 is shown as comprising a roller which is mounted on a pin carried bythe links 54. I prefer to mount the elenient55 in this manner so thatwhen it is out of locking engagement with the surfaces 26 and a minimumand element.

made wide enough of the outer end ensuring the even wear of the lThelinks 54 are preferably to overlap the opposite sides 42, which bellcrank is pivot-v paratus are shown in with the vehicle empty.

In eifectiing an application of the brake, fluid under pressure suppliedto the pipe and passage 13 flows to the brake cylinder 6 past theunseated valve 9 and its fluted stem, through diaphragm vchamber 14 andpassage and pipe 15. Now when the brake cylinder pressure in the chamberphragm 8, is suflicient to overcome-the opposing pressure of theadjusted spring 18, the diaphragm will ileX toward the right hand,permitting the pressure of the spring l1 to move the valve 9 to itsseated position, closing 01T the further supply of fluid under pressureto the brake cylinder and thus limiting the brake cylinder pressure tothat desired for bringing an empty vehicle to a stop.

Now when the empty vehicle has been brought to a stop and it is desiredto open the door, iluid under pressure is supplied to the door openingside of the door engine 7 through pipe 32, and causes the door engine tooperate to door open position.

Fluid under pressure thus supplied to the pipe and passage 32 also flowsto the chamber 31 in the strut cylinder device 4 and also to the cham-'-ber 47 in the casing of the locking mechanism 5.

The fluid under pressure building up in the piston chamber 31 forces thepiston 27 and strut 28 outwardly against the pressure exerted by thespring 34 until the piston is brought to a stop by its engagement with ashoulder 59 formed in the casing. Since the locking element 55 is inlocking engagement with arm 25 and Vlug 58, and the arm 22 is inengagement with the bolt 20 secured to the spring-pressed plunger 19,the shaft 23, Varm 35 and link 36 are held against movement, so that thepin 38 will act as a fulcrum for the lever 29 as the lever is moved bythe strut 28. With the pin 38 as a fulcrum, the lever 29 operates topush the rod 39 towardthe right hand rotating the bell crank so as tobring the roller 44 carried by the arm 43 thereof into engagement withthe portion 2 of thefvehicle truck.

Now, when the pressure of fiuid building up in the piston chamber 47 inthe casing of the locking mechanism, and acting on one side of thepiston 45, is sufcient to overcome the pressure exerted on the otherside of the piston by the spring 49, the piston and piston stem 46 willmove downwardly until they are brought to a stop by the piston engaginga shoulder formed in the casing. This downward movement of the stem 46causes the lever 50 to rock on the pin 51 so that the links 54 are movedupwardly carrying the locking element 55 out of locking engagement withthe arm 25 and lug 58.

If the load on the vehicle is now increased, the truck springs will becompressed and the vehicle body will move downwardly'relative to thetruck, so that the portion 2 of the truck, acting on the arm 43 throughthe medium of the roller 44, causes an anti-clockwise movement of thebell crank, which exerts a force throughthe rod 39 to cause ananti-clockwise rotation of the lever 29,` with the pivot pin 39 'asafulcrum, the strut 28 being maintained in its extreme outer position bythe pressure of uid in the piston chamber -31 acting on the piston 27.

When the lever 29 is thus rotated, the lower end thereof, through themedium of the link 36, pulls the arm 35 toward the right hand, rocking`the shaft 2 3 and arm 25 in a clockwise direction,

their adjusted positions 14, acting on one side of the dia-,

the locking element 55 offering no resistance to such movement of thearm. since it is maintained out Yof wedging engagement with the arm andlug 58 by the pressure of fluid in the piston chamber 47 acting on thepiston 45.

As the shaft 23 is thus being rotated, the arm 22.secured thereto,through the medium of the bolt 20 forces the plunger 19 inwardlycompressing the spring 18 correspondingly with the increase in the loadon the vehicle.

When the vehicle has been loaded, the pipe 32 is vented to theatmosphere to permit the door engine to operate to close the door of thevehicle.

With the pipe 32 thus vented to the atmosphere the piston chambers 31and 47-are consequently Vented. pressure of the spring 49 is such thatit will cause the piston to move upwardly beforethe strut piston 2'7begins to move toward the left hand. As the piston 45 is moved upwardlyby the pressure of the spring 49, the piston rod 46 causes the lever tobe rocked in a clockwise direction about the pin 51, moving the links 54and locking. element carried by the links, downwardly. When the element55 is thus moved, it is brought into locking engagement with thesurfaces 26 and 56 of the arm 25 and lug 58, respectively.

Now, when the pressure of fluid in the piston chamber 31 has reducedsufficiently, the pressure of the spring 34 will cause the strut piston27 to return to its extreme left hand position as shown in Fig. 1 and inso doing, operates the strut 28, lever 29, rod 39 and bell crank in sucha manner that the roller carried by the arm 43 of the bell crankwill bemoved out of engagement with the portion 2 of the vehicle truck.

` With the locking element 55 in locking engagement with the arm 25 andlug 58 as above described, the outward pressure of the spring 18 actingthrough the plunger 19, bolt 20, arm 22 and shaft 23, will not affectthe adjustment of the arm 25 so that the adjustment ofthe spring 18 ismaintained.

When the apparatus is thus adjusted for a loaded vehicle, the brakecylinder pressure obtained in effecting a subsequent Vbrake applicationwill be greater than that obtained when the vehicle was empty and thisis due to the increased pressure of the spring 18l on the flexiblediaphragm 8.

Should the load on the 'vehicle be decreased when the locking element 55is out of locking engagement with thearm 25 yand lug 58, the pressure ofthe spring .18 will force vthe plunger 19 and bolt 20 outwardly,rotating the arm 22 and consequently the shaft 23, arms25 and 35 inananti-clockwise direction. This movement of the arm 35 also causesthelever 29 to rotate in a clockwise direction about the pin 30 kso thatas the load is decreased, the roller 44'wll be maintained in engagementwiththe portion 2 of the truck.

Now, when the pipe 32 is vented to the atmosphere, the apparatus willoperate as before described to maintain the adjustment of the springWhilst the friction surface 26 of the arm 25 may be of any suitableshape, I prefer to make arc of a circle struck from a center above apoint corresponding with the axis of the shaft 23. It will be seen thatwith the friction surface 26 so formed, the friction element 55 will becaused to engage the friction l surface 56 of the lug 58 at differentpoints along It will here be noted that the` a portion of the length ofthe surface in locking the ,apparatus in its various adjusted positions,thus ,eiectively guarding against the roller forming grooves in thesurface 56.

While vone illustrative embodiment of the invention has been describedin detail, it is not my intention to limit its scope to that embodimentor otherwise than by the terms of the appended claims.

Having now described my invention, j what I claim as new and desire tosecure by Letters Patent, is: Y

1.v In a variable load brake apparatus for a vehicle, the combinationwith means for adjusting the braking power according to the load on thevehicle, of fiuid pressure controlled wedge means for maintaining theadjusting means in an adjusted position.

2. In a variable load brake apparatus for a vehicle, the combinationwith means for adjusting the braking power according to the load on thevehicle, of a locking wedge element movable into frictional lockingengagement with the adjusting means for maintaining the adjusting meansin an adjusted position.

3. In a variable load brake apparatus for a vehicle, the combinationwith means for adjusting the braking power, according to the load on thevehicle, of a locking wedge element movable into frictional lockingengagement with the adjusting means for maintaining the adjusting meansin an adjusted position, and a spring for moving said locking element.

4. In a variable load brake apparatus for a vehicle, the combinationwith means for adjusting the braking power according to the load on thevehicle, of a locking wedge element movable into frictional lockingengagement with the adjusting means for maintaining the adjusting meansin an adjusted position, and movable out of locking vengagement topermit the adjusting means to operate to another adjusted position, andpressure sensitive means for controlling the operation of said lockingelement. 5. In a variable' load brake apparatus for a vehicle, thecombination with means for adjusting the braking power according to theload on the vehicle, of a wedge element for locking said means in anadjusted position, and means operated by fluid under pressure foroperating said element to release the adjusting means. V

6. In a variable load brake apparatus for a vehicle, the combinationwith means for adjusting the braking power according to theload on thevehicle, of a movable friction element included in said means, astationary friction element, and a locking element movable into lockingengagement with said friction elements for maintaining said means in anadjusted position.

7. In a variable load brake apparatus for a vehicle, the combinationwith means for adjusting the/braking power according to the load on thevehicle, of amovable friction element included in said means, astationary friction element, and a roller movable into wedgingengagement with said friction elements for maintaining said means in anadjusted position.

8. In a lvariable load brake apparatus for a vehicle, the combinationwith means for adjusting the braking power according to the load on thevehicle, of an adjustable friction element included in said means, astationary friction element, a locking member interposed between andmovable relative to said friction elements, mechanism for moving saidlocking member, and

means included in; said stationary frictionrelement for forcing saidlocking member into frictional locking engagement with saidradjustablefriction element when said locking member is moved in one directionrelative to said friction elements for maintaining the adjusting meansin anv adjusted position.

9. In a variable load brake apparatus for a vehicle, the combinationwith means for adjusting the braking power according to the load on thevehicle, o-f an adjustable element included in said means, a stationaryelement, said elements having oppositely disposed converging frictionsurfaces, a locking member adapted to be wedged between said frictionsurfaces for maintaining the adjusting ymeans in an adjusted position,and means for operating said locking member.

10. In a variable load brake apparatus for a vehicle, the combinationwith means for adjustingthe braking power according to the load on thevehicle, of an adjustable element included in said means, a stationaryelement, said element having oppositely disposed converging frictionsurfaces, a locking member adapted to be wedged between said frictionsurfaces for maintaining the adjusting means in an adjusted position, alink for operating said locking element, a lever for operating Vsaidlink, and pressure sensitive means for operating said lever.

11. In a variable load brake apparatus for a vehicle, the combinationwith means for adjusting the braking power according to the load on thevehicle, of a movable friction element included; in said means, astationary friction element, a locking element movable intoI frictionallocking engagement with said friction elements for maintaining theadjusting means in an adjusted position, and mechanism for, operatingsaid locking element, said mechanism comprising a link cooperating withat least one of said friction elements for guiding said locking elementas it is operated.

12. In a variable load brake apparatus for a vehicle, Ythe combinationwith means for adjusting the braking power according to the load on thevehicle, of an adjustable element included in said means, a stationaryelement, said elements having oppositely disposed converging frictionsurfaces, a locking member adapted to be wedged between said frictionsurfaces for maintaining the adjusting means in an adjusted position andadapted to be moved out of its wedged position to permit the adjustingmeans to operate to another adjusted position, and fluid pressurecontrolled means for operating said locking member.

13. In -a variable load brake apparatus for a vehicle, the combinationwith means fo-r adjusting the braking power according toy the load onthe vehicle, of an adjustable element included in said means, astationary element, said elements having oppositely disposed convergingfriction surfaces, a roller adapted to bev wedged between saidfrictionsurfaces for locking the adjusting means in an adjusted position, :andmeans for moving -said locking member into and out of its wedgedVposition.

14. In a variable loadbrake apparatus-fora vehicle, the combination withmeans for adjusting the braking power according to the `load on thevehicle, of a rockable element included in said means adjustableaccording to the load on the vehicle, and a locking element movable intolocking engagement with said rockableelement for locking said means inan adjusted position. j

15. In av variable load brake apparatus for a vehicle, the combinationwith means for adjusting the braking power laccording to the lload onthe vehicle, of a rockable element included in said means adjustableaccording to the load on the vehicle, and a locking element wedged intolocking engagement with said rockableelement for locking said means inan adjusted position.

16. In a variable load brake apparatus fora vehicle, the combinationwith means for'a'djusting the braking power according to the load'on thevehicle, of a rockable friction element included in said meansadjustable according to the load on the vehicle, and a lockingelementimovable into frictional locking engagement with said rockablefriction element for locking said means in an adjusted position. f Y*17. In a variable load brake apparatus for a vehicle, the combinationwith means for radjusting the braking powervaccording to the load on thevehicle, of an adjustable member included in said means having a curvedfriction locking surface and adjustable according to lthe load on thevehicle, and friction locking means movable into frictional lockingengagement with said curved friction face for maintaining the adjustingmeans in an adjusted position.

18. In a variable load brake apparatus for `a vehicle, the combinationwith means for adjusting thefbraking power according to the load on thevehicle, of a cam included in said means adjustable according to theload on the vehicle and having a friction locking surface, and meansoperable into frictional locking engagement with the friction lockingsurface of said cam for maintaining the adjusting means in an adjustedposition.

19. In a variable load brake apparatus "for a vehicle, the combinationIwith means for adjusting the braking power according to the :load onthe vehicle, of a `rockable element included in said means adjustableaccording to the load on the vehicle, a locking element movable intolocking engagement with said rockable element for locking said means inan adjusted position and movable out of locking engagement to permit theadjustmentof said rockable member, and fluid pressure means forcontrolling the operation of said locking element.

EWING K. LYNN.

